Limits...
Embryonic frog epidermis: a model for the study of cell-cell interactions in the development of mucociliary disease.

Dubaissi E, Papalopulu N - Dis Model Mech (2010)

Bottom Line: These cells express high levels of ion channels and transporters; therefore, we suggest that they are analogous to ionocytes found in transporting epithelia such as the mammalian kidney.Depletion of ionocytes by foxi1e knockdown has detrimental effects on the development of multiciliated cells, which show fewer and aberrantly beating cilia.These results reveal a newly identified role for ionocytes and suggest that the frog embryonic skin is a model system that is particularly suited to studying the interactions of different cell types in mucociliary, as well as in secretory and transporting, epithelia.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Life Sciences, University of Manchester, Manchester, UK.

ABSTRACT
Specialised epithelia such as mucociliary, secretory and transporting epithelia line all major organs, including the lung, gut and kidney. Malfunction of these epithelia is associated with many human diseases. The frog embryonic epidermis possesses mucus-secreting and multiciliated cells, and has served as an excellent model system for the biogenesis of cilia. However, ionic regulation is important for the function of all specialised epithelia and it is not clear how this is achieved in the embryonic frog epidermis. Here, we show that a third cell type develops alongside ciliated and mucus-secreting cells in the tadpole skin. These cells express high levels of ion channels and transporters; therefore, we suggest that they are analogous to ionocytes found in transporting epithelia such as the mammalian kidney. We show that frog ionocytes express the transcription factor foxi1e, which is required for the development of these cells. Depletion of ionocytes by foxi1e knockdown has detrimental effects on the development of multiciliated cells, which show fewer and aberrantly beating cilia. These results reveal a newly identified role for ionocytes and suggest that the frog embryonic skin is a model system that is particularly suited to studying the interactions of different cell types in mucociliary, as well as in secretory and transporting, epithelia.

Show MeSH

Related in: MedlinePlus

Loss of ionocytes affects the development of ciliated and goblet cells. (A,B) SEM and (C,D) TEM images of stage 27 tadpole epidermis of control and foxi1e-ATG-MO-injected embryos, as indicated. (A) Knockdown of foxi1e causes loss of cells with apical pits (ionocytes) but ciliated cells are still present. Scale bars: 25 μm. (B) High-magnification images reveal that ciliated cells in foxi1e knockdown embryos possess fewer cilia than controls. Scale bars: 10 μm. (C) TEM images show that, in the control, basal bodies are located beneath the apical membrane (arrowheads), whereas, in the foxi1e morphant embryos, numerous basal bodies are abnormally located deep in the cytoplasm (arrowheads). Scale bars: 1 μm. (D) Goblet cells develop an increased number of cellular protrusions, resembling microvilli, in the foxi1e morphant embryos (arrowheads) compared with goblet cells of control embryos. Scale bars: 1 μm (control); 500 nm (foxi1e ATG MO).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3046089&req=5

f7-0040179: Loss of ionocytes affects the development of ciliated and goblet cells. (A,B) SEM and (C,D) TEM images of stage 27 tadpole epidermis of control and foxi1e-ATG-MO-injected embryos, as indicated. (A) Knockdown of foxi1e causes loss of cells with apical pits (ionocytes) but ciliated cells are still present. Scale bars: 25 μm. (B) High-magnification images reveal that ciliated cells in foxi1e knockdown embryos possess fewer cilia than controls. Scale bars: 10 μm. (C) TEM images show that, in the control, basal bodies are located beneath the apical membrane (arrowheads), whereas, in the foxi1e morphant embryos, numerous basal bodies are abnormally located deep in the cytoplasm (arrowheads). Scale bars: 1 μm. (D) Goblet cells develop an increased number of cellular protrusions, resembling microvilli, in the foxi1e morphant embryos (arrowheads) compared with goblet cells of control embryos. Scale bars: 1 μm (control); 500 nm (foxi1e ATG MO).

Mentions: To gain a greater insight into the impact of foxi1e knockdown on the mucociliary epidermis as a whole, SEM and TEM were performed on morphant embryos. These showed that small cells with apical openings were absent from the surface. Just as shown by immunofluorescence, the SEM images indicated that the major defect was in the ciliated cells (Fig. 7A,B). The cilia are less abundant and seem to be shorter than in control embryos. TEM images showed that the ciliated cells in the foxi1e morphant embryos possessed numerous basal bodies, but these were abnormally located deep in the cytoplasm (Fig. 7C, marked by arrowheads). By contrast, in the controls, basal bodies were found close to the apical membrane, where they normally dock (Park et al., 2008). Thus, it is very likely that the reduction in the number of cilia is due to failure of basal bodies to migrate and/or dock to the apical side. There were also some noticeable changes in the morphology of the cells surrounding the ciliated cells. These were more difficult to describe but it seems that these cells have developed excessive villi or protrusions. Indeed, TEM images also showed that, in experimental animals, goblet cells harboured cytoplasmic protrusions resembling microvilli, which seemed covered by a dense material (Fig. 7D, arrowheads). In addition, goblet cells were larger compared with controls (also seen by xeel staining, Fig. 6D).


Embryonic frog epidermis: a model for the study of cell-cell interactions in the development of mucociliary disease.

Dubaissi E, Papalopulu N - Dis Model Mech (2010)

Loss of ionocytes affects the development of ciliated and goblet cells. (A,B) SEM and (C,D) TEM images of stage 27 tadpole epidermis of control and foxi1e-ATG-MO-injected embryos, as indicated. (A) Knockdown of foxi1e causes loss of cells with apical pits (ionocytes) but ciliated cells are still present. Scale bars: 25 μm. (B) High-magnification images reveal that ciliated cells in foxi1e knockdown embryos possess fewer cilia than controls. Scale bars: 10 μm. (C) TEM images show that, in the control, basal bodies are located beneath the apical membrane (arrowheads), whereas, in the foxi1e morphant embryos, numerous basal bodies are abnormally located deep in the cytoplasm (arrowheads). Scale bars: 1 μm. (D) Goblet cells develop an increased number of cellular protrusions, resembling microvilli, in the foxi1e morphant embryos (arrowheads) compared with goblet cells of control embryos. Scale bars: 1 μm (control); 500 nm (foxi1e ATG MO).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3046089&req=5

f7-0040179: Loss of ionocytes affects the development of ciliated and goblet cells. (A,B) SEM and (C,D) TEM images of stage 27 tadpole epidermis of control and foxi1e-ATG-MO-injected embryos, as indicated. (A) Knockdown of foxi1e causes loss of cells with apical pits (ionocytes) but ciliated cells are still present. Scale bars: 25 μm. (B) High-magnification images reveal that ciliated cells in foxi1e knockdown embryos possess fewer cilia than controls. Scale bars: 10 μm. (C) TEM images show that, in the control, basal bodies are located beneath the apical membrane (arrowheads), whereas, in the foxi1e morphant embryos, numerous basal bodies are abnormally located deep in the cytoplasm (arrowheads). Scale bars: 1 μm. (D) Goblet cells develop an increased number of cellular protrusions, resembling microvilli, in the foxi1e morphant embryos (arrowheads) compared with goblet cells of control embryos. Scale bars: 1 μm (control); 500 nm (foxi1e ATG MO).
Mentions: To gain a greater insight into the impact of foxi1e knockdown on the mucociliary epidermis as a whole, SEM and TEM were performed on morphant embryos. These showed that small cells with apical openings were absent from the surface. Just as shown by immunofluorescence, the SEM images indicated that the major defect was in the ciliated cells (Fig. 7A,B). The cilia are less abundant and seem to be shorter than in control embryos. TEM images showed that the ciliated cells in the foxi1e morphant embryos possessed numerous basal bodies, but these were abnormally located deep in the cytoplasm (Fig. 7C, marked by arrowheads). By contrast, in the controls, basal bodies were found close to the apical membrane, where they normally dock (Park et al., 2008). Thus, it is very likely that the reduction in the number of cilia is due to failure of basal bodies to migrate and/or dock to the apical side. There were also some noticeable changes in the morphology of the cells surrounding the ciliated cells. These were more difficult to describe but it seems that these cells have developed excessive villi or protrusions. Indeed, TEM images also showed that, in experimental animals, goblet cells harboured cytoplasmic protrusions resembling microvilli, which seemed covered by a dense material (Fig. 7D, arrowheads). In addition, goblet cells were larger compared with controls (also seen by xeel staining, Fig. 6D).

Bottom Line: These cells express high levels of ion channels and transporters; therefore, we suggest that they are analogous to ionocytes found in transporting epithelia such as the mammalian kidney.Depletion of ionocytes by foxi1e knockdown has detrimental effects on the development of multiciliated cells, which show fewer and aberrantly beating cilia.These results reveal a newly identified role for ionocytes and suggest that the frog embryonic skin is a model system that is particularly suited to studying the interactions of different cell types in mucociliary, as well as in secretory and transporting, epithelia.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Life Sciences, University of Manchester, Manchester, UK.

ABSTRACT
Specialised epithelia such as mucociliary, secretory and transporting epithelia line all major organs, including the lung, gut and kidney. Malfunction of these epithelia is associated with many human diseases. The frog embryonic epidermis possesses mucus-secreting and multiciliated cells, and has served as an excellent model system for the biogenesis of cilia. However, ionic regulation is important for the function of all specialised epithelia and it is not clear how this is achieved in the embryonic frog epidermis. Here, we show that a third cell type develops alongside ciliated and mucus-secreting cells in the tadpole skin. These cells express high levels of ion channels and transporters; therefore, we suggest that they are analogous to ionocytes found in transporting epithelia such as the mammalian kidney. We show that frog ionocytes express the transcription factor foxi1e, which is required for the development of these cells. Depletion of ionocytes by foxi1e knockdown has detrimental effects on the development of multiciliated cells, which show fewer and aberrantly beating cilia. These results reveal a newly identified role for ionocytes and suggest that the frog embryonic skin is a model system that is particularly suited to studying the interactions of different cell types in mucociliary, as well as in secretory and transporting, epithelia.

Show MeSH
Related in: MedlinePlus